Dengue viruses cause a significant public health burden in tropical regions of the world and now threaten to proliferate in more temperate climates. There is currently no acceptable vaccine to prevent dengue. This project seeks to develop a DNA vaccine that will prevent dengue fever. Existing dengue DNA vaccine constructs will be improved by the addition of the intracellular trafficking sequences of the lysosome associated membrane protein (LAMP) to dengue genes on the vaccine plasmid. These sequences target the antigen to MHC class II associated intracellular compartments and enhance the immune response of vaccinated animals. The vaccines will be further improved by delivering plasmids in sustained release microspheres made from poly(phosphoester) and other polymers under development. These preparations are expected to increase the efficiency of DNA immunization and reduce the number of doses required. The microspheres will also be used to co-deliver granulocyte- macrophage colony stimulating factor (GMCSF) and other cytokines selected to enhance the appropriate immune response. Formulations that are effective in inducing neutralizing antibodies in mice will be tested in non-human primate studies. Selection of the candidates most likely to succeed in humans will be made based on the ability of vaccines to induce immunity that prevents viremia in non-human primates after challenge with live dengue virus. The results of this project will be directed to a vaccine formulation chosen to enter GMP production for human trials.